Management of the borderline QTc interval in the psychiatric patient: results of a drug surveillance program

Purpose It is not known if in low-risk populations a drug-induced bor-derline-QTc (bQTc, males: 440-500ms, females: 460-500ms) predicts adverse outcomes. We assessed clinical impact, prevalence and risk factors for bQTc in a sample of schizophrenic outpatients taking at least 1 antipsychotic in 24 months.Methods All the schizophrenic outpatients followed by our ward were evaluated (history,electrolytes, ECG). Subjects with possible LQT-syn-drome, use of other QT-elonging drugs, ECG alterations or dyselectroly-temias were excluded. 193 consecutive patients were selected and re-assessed at 9-24 months. Risk factors and hazard were evaluated with logistic regression, Kaplan-Meier and Cox models.Results No deaths, syncope or QTc>500ms were registered. 18% of the sample had a bQTc at the admission. Incomplete RBBB (iRBBB) [OR=3.14; 95%CI:1.473-6.694, p<0.05] and association of >3 drugs [OR=1.87; 95%CI:1.045-3.346, p<0.05] were the strongest risk fac-tors for bQTc. Subjects with normal ECG under 1-2 drugs had higher hazard than ones with iRBBB taking >3 drugs [time-to-bQTc: 20.6 vs. 13.2 months, p<0.05; HR=2.50; 95%IC:1.49-4.21, p<0.05].Conclusions Among otherwise healthy schizophrenics, control of symptoms should be pursued first, restraining precipitating or predis-posing factors. bQTc is frequent, related to iRBBB and multiple anti-psychotics.